1. Field of the Invention
The present invention relates to a disc recording/playback apparatus suitably applied to a master disc unit for producing a cutting master disc which is an original disc used for manufacturing a large number of compact discs (CD) and mini-discs (MD) in a music disc manufacturing factory and more particularly to a disc recording/playback apparatus adapted to be able to display a compressed envelope waveform of music signal to be recorded.
2. Description of the Related Art
A recording medium for a cutting master which is an original disc of compact discs and mini-discs has to be provided in manufacturing a large number of compact discs and mini-discs in a music disc manufacturing factory. Normally a magnetic tape is used for this recording medium. FIG. 36 is a system block diagram of a main part of a prior art master recording apparatus 10 used for creating the original disc.
In FIG. 36, normally a digital video tape recorder (U-matic video tape recorder) is used in a multi-channel tape recorder 11 in which source music signals are recorded to create an original audio tape in which the music signals are recorded. Because the original audio tape is multi-channel recorded, a master recorder 12 converts it into two channel signals.
A master tape is then supplied to an editing unit 13 to implement editing operations necessary for convertion into a format conforming to the type of disc to be cut to create a final master tape for cutting. All disc manufacturing factories produce corresponding compact discs and cassette tapes using this master tape.
Incidentally, with the recent spread of music discs, the demand for using discs as recording mediums for original discs has strengthened. By using the disc as an original, original signals can be recorded linearly without compressing them and edited on one original disc without destroying them, making the disc an original.
In using the disc as the original instead of the tape described above, it is helpful in editing operations, such as determining editing points, if broad envelope changes of music signals recorded in the disc can be grasped when carrying out editing operations using the disc.